Page 115 - ICSE Math 4

Plane Figures

We know that any shape is made up of either straight or curved lines. Based on that there

are fi ve basic shapes. They are circle, triangle, square, rectangle, and oval. These are fl at
and closed two-dimensional (2D) shapes, and are called plane fi gures.

Let’s study some proper es related to these fi gures.

• A side is a straight line joining two corners lying adjacent (side by side) to each other
that makes up the shape. A side can also be called an edge in a plane fi gure.

• A corner in a fi gure is the point where two straight lines meet. A corner can also be
called a vertex (plural: ver ces) where two sides meet.

Let’s know more about such closed fi gures.
Square

A D
A square is a plane closed fi gure that has 4 equal sides or edges
and 4 corners or ver ces. Vertex
In the given square, all the four sides AB, BC, CD and DA are equal,

i.e., AB = BC = CD = DA. B C
A, B, C and D are the four ver ces of the square.

Rectangle

A rectangle is a plane closed fi gure that has 4 sides in A Side (long) D
which only the opposite sides or edges are equal. It has Vertex
4 corners or ver ces. Side (short)
In the given rectangle, sides AB = DC and BC = AD.
B C
A, B, C and D are the four ver ces of the rectangle.

Triangle
A
Vertex
A triangle is a plane closed fi gure that has 3 sides or edges and
3 corners or ver ces. Side
In the given triangle, the three sides are AB, BC and CA.
B C
A, B and C are the three ver ces of the triangle.

Circle

A circle is a plane closed fi gure that has no sides or edges and corners or
ver ces.

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